Conservative challenger Rick Santorum said he quitted the Republican presidential nomination race on Tuesday, effectively making front-runner Mitt Romney the certain Republican nominee.
"We made a decision over the weekend that while the presidential race for us is over, and I will suspend my campaign effective today, we are not done fighting," CNN quoted Santorum as saying.
Santorum, the former senator of Pennsylvania, said he had expected to continue his campaign until the primary in Pennsylvania April 24, but had decided to quit after his severely ill 3-year-old daughter, Bella, was taken to hospital.
“This game is a long, long, long way from over. We are going to continue to go out there and fight to make sure that we defeat President Barack Obama,” Santorum added.
The withdrawal announcement was made after Santorum’s recent primary losses and amid poll figures indicating that he might lose the primary in his home state of Pennsylvania.
Though Romney still has to win several hundred delegates to secure his nomination, Santorum’s withdrawal clears the path for him. The two other Republican candidates still in the race - former House Speaker Newt Gingrich and Texas Rep. Ron Paul - are not considered a factor.
CNN's latest estimate of the GOP delegate tally shows Romney with 659, Santorum with 275, Gingrich with 140 and Paul with 71. It takes 1,144 delegates to clinch the nomination.
Romney thanked Santorum for being “an able and worthy competitor” shortly after the announcement was made.
"Senator Santorum is an able and worthy competitor, and I congratulate him on the campaign he ran. He has proven himself to be an important voice in our party and in the nation. We both recognize that what is most important is putting the failures of the last three years behind us and setting America back on the path to prosperity," he said.